Process for the preparation of porous polymers and polymers obtainable thereof

ABSTRACT

A process for preparing porous olefin polymers comprising bringing into contact in a polymerization reactor, at a temperature T 1 , one or more olefins of the formula (I) CH 2 ═CHR 1 , R 1  being hydrogen, a C 1 –C 20 -alkyl or a C 6 –C 12 -aryl group, with a catalyst obtained by reacting a solid catalyst component in the form of spheroidal particles comprising a compound of Ti or V not containing metal-π bonds and a Mg halide, optionally containing one or more electron donor compounds, with an aluminum-alkyl (Al-alkyl) compound, then raising the temperature up to the polymerization temperature, said process being characterized in that: a) if the temperature T 1  is lower than 40° C., the temperature is raised up to the polymerization temperature is such a way that, for a time of at least one minute after the introduction temperature in such a way that, for a time of at least one minute after the introduction of the catalyst system into the reactor, the temperature of the reaction T 2  fulfills the following condition of formula (II) wherein m is the time expressed in minutes employed for reaching the temperature T 2 ; or b) if temperature T 1  is 40° C. or higher, the reactor is maintained for a time of at least one minute at a temperature of at least 40° C.

This application is the U.S. national phase of International ApplicationPCT/EP01/15394, filed Dec. 21, 2001.

The present invention relates to a process for preparing olefinpolymers, in particular homopolymers or copolymers of propylene, havinghigh porosity and good pore size distribution. The present inventionfurther relates to the use of said highly porous polymers as support fora catalyst component in a process for the polymerization of olefins andfor the preparation of polymer reactor blends.

Catalysts comprising a transition metal supported on an inert inorganiccarrier are well known for their use in the preparation of olefinpolymers with morphological characteristics.

For instance, U.S. Pat. Nos. 4,298,718 and 4,399,054 describe catalystsof titanium halide supported on magnesium halide and their use in thepolymerization of olefins.

In the European Patent Application EP 0 789 037 it is disclosed apolymerization process for the production of porous propylene polymers.Although the polymers obtained thereof have spherical particle form, theporosity of these polymers is still unsatisfactory.

Also known are catalysts for the polymerization of olefins wherein atransition metal is supported on an inert organic carrier.

For instance, EP-A-0 295 312 discloses catalysts of metallocenessupported on polymeric material for use in the polymerization ofolefins. Although the obtained polymers have uniform particle size, theporosity values are not sufficiently high.

European Patent Applications EP 0 720 629 and EP 0 742 801 disclose amultistage process for the polymerization of olefins. In a first stage apolymer support is formed. In a second stage, the polymeric materialpreviously formed is contacted with a metallocene compound. In a furtherstage, the polymerization is carried out in the presence of thesupported polymer obtained in the previous steps. When said process isused for the preparation of heterophasic copolymers, such as rubberycopolymers, it is not satisfactory and can be improved so that lessfouling occurs. Further, the proccessability of the obtained polymer canstill be improved.

Thus, it would be desirable to provide porous polymers having improvedporosity values and pore size distribution (P.S.D.) which, when used ascarrier for a multistage process, avoid the above mentioned and otherproblems.

It has been surprisingly found that it is possible to obtain highlyporous propylene polymers having improved pore size distribution in theform of spherical particles, which solve the above and other problems.

The present invention provides a process for preparing porous olefinpolymers comprising putting into contact in a polymerization reactor, ata temperature T¹, one or more olefins of formula CH₂═CHR¹, R¹ beinghydrogen, a C₁–C₂₀-alkyl or a C₆–C₁₂-aryl group with a catalyst obtainedby reacting a solid catalyst component in the form of spheroidalparticles comprising a compound of Ti or V not containing metal-π bondsand a Mg halide, optionally containing one or more electron donorcompounds, with an aluminum-alkyl (Al-alkyl) compound, then raising thetemperature up to the polymerization temperature, said process beingcharacterized in that:

-   -   (I) if the temperature T¹ is lower than 40° C., the temperature        is raised up to the polymerization temperature in such a way        that, for a time of at least one minute after the introduction        of the catalyst system into the reactor, the temperature of the        reactor T² fulfills the following condition:

$\frac{T^{2} - T^{1}}{m} > 8$wherein m is the time expressed in minutes employed for reaching thetemperature T²; or

-   -   (II) if the temperature T¹ is 40° C. or higher, the reactor is        maintained for a time of at least one minute at a temperature of        at least 40° C., preferably at a temperature higher than 45° C.,        more preferably at a temperature ranging from 45° C. to 65° C.

Preferably T¹ ranges from 28° C. to the polymerization temperature,preferably from 28° C. to 120° C., more preferably from 40° C. to 90° C.

Preferably in the condition (I) the polymerization temperature isreached in a time ranging from 1 to 10 minutes, more preferably from 2to 6 minutes.

Preferably conditions (I) or (II) have to be fulfilled for 1 to 5minutes, more preferably for at least 3 minutes.

Preferably in the condition (I)

${\frac{T^{2} - T^{1}}{m} > 9},$more preferably

${\frac{T^{2} - T^{1}}{m} > 10};$still more preferably

${\frac{T^{2} - T^{1}}{m} > 15};$even more preferably

$19 < \frac{T^{2} - T^{1}}{m} < 25.$

The catalyst system, either as such or together with a suitablehydrocarbon solvent, such as hexane or benzene, is added into thepolymerization medium, which has the above mentioned temperature range.Subsequently, the temperature is varied according to the process of thepresent invention until the polymerization temperature is obtained.

The polymerization is carried out at a temperature ranging generallybetween 40° and 150° C., preferably between 60° C. and 90° C. Thepolymerization can be carried out at atmospheric pressure or higher.

The process of the invention can be carried out with low conversiondegree, such that a prepolymer is obtained in an amount greater than 0.5g per g of solid catalyst component and up to 2000 g per g of solidcatalyst component. Preferably, the amount is between 5 g and 500 g perg of catalyst component, and more preferably between 10 g and 100 g perg of catalyst component.

The prepolymerization is preferably carried out in a liquid phasecontaining an inert hydrocarbon diluent, such as propane or hexane or ingas phase.

Heterogeneous Ziegler/Natta solid catalyst components in the form ofspherical particles are, for instance, obtained by supporting Ti or Vcompounds on Mg halide, preferably on active MgCl₂, which is inspherical form. Examples of these kind of catalysts are disclosed, forinstance, in U.S. Pat. Nos. 4,399,054 and 5,221,651, the disclosure ofwhich is incorporated herein by reference.

The catalyst component may also contain one or more electron-donors,either internal or external. An electron-donor is particularly usefulwhen the catalyst is employed in the synthesis of stereoregular polymersof propylene and other alpha-olefins, such as 1-butene, where highstereospecificity is required to obtain polymers with an isotacticityindex of greater than 90, or even greater than 98.

The electron-donor compound can be selected from ethers, esters, amines,ketones and the like. Non-limiting examples are alkyl esters,cycloalkyls and aryls of polycarboxylic acids, such as phthalic andmaleic esters and ethers, such as those which are described inEP-A-45977, the disclosure of which is incorporated herein by reference.The external donor can be the same or can be different from the internaldonor. A particularly preferred class of external donor comprises alkylor alkoxy silanes of formula R^(1b) _(c)R^(2b) _(d)Si(OR^(3b))_(e)wherein R^(1b), R^(2b) and R^(3b) equal to or different from each otherare C₁–C₂₀ hydrocarbon radical, c and d range from 0 to 2 being c+dequal to 1 or 2 and e is 2 or 3 being c+d+e=4. When using diethercompounds as those as disclosed in the European patent applicationEP-A-361494, the stereospecificity of the catalyst is sufficiently high,such that the presence of an external-donor is not required.

The compounds of Ti or V are selected preferably from TiCl₄, TiCl₃ orTi(OR²)_(f)X_(g-f), R² being a hydrocarbon radical containing up to 15carbon atoms or a —COR³ group, R³ being a hydrocarbon radical containingup to 15 carbon atoms, X being a halogen, f ranges from 1 to 4 and g isthe valence of titanium. Suitable vanadium based compounds are VCl₃,VCl₄, VOCl₃ and vanadyl halides. Most preferably, TiCl₄ or TiCl₃ isused.

The process for the preparation of the porous propylene polymersaccording to the present invention is also carried out in the presenceof a co-catalyst, such as an aluminum-alkyl compound (Al-alkyl)compound. Non-limiting examples of aluminum compounds are Al(Me)₃,Al(Et)₃, AlH(Et)₂, Al(iBu)₃, AM(iBu)₂, Al(iHex)₃, Al(iOct)₃, AlH(iOct)₂,Al(C₆H₅)₃, Al(CH₂—CH(Me)CH(Me)₂)₃, Al(CH₂C₆H₅)₃, Al(CH₂CMe₃)₃,Al(CH₂SiMe₃)₃, Al(Me)₂iBu, Al(Me)₂Et, AlMe(Et)₂, AlMe(iBu)₂, Al(Me)₂iBu,Al(Me)₂Cl, Al(Et)₂Cl, AlEtCl₂ and Al₂(Et)₃Cl₃, wherein Me=methyl,Et=ethyl, iBu=isobutyl, iHex=isohexyl, iOct=2,4,4-trimethyl-pentyl. Theabove mentioned Al-alkyl compounds can be used either alone or inmixtures thereof.

Amongst the above aluminum compounds, trimethylaluminum (TMA),triisobutylaluminum (TIBAL) and tris(2,4,4-trimethyl-pentyl)aluminum(TIOA) are preferred.

The catalytic component used in the process of the present invention isin the form of spherical particles having an average diameter between 10and 150 μm. With the term spherical particles is meant particles havinga ratio between maximum diameter and minimum diameter of less than 1.5and preferably less than 1.3. Suitable methods for the preparation ofsaid components in spherical form are described in U.S. Pat. Nos.5,221,651 and 4,399,054.

A further aspect of the present invention is a polymer obtainable by aprocess according to the present invention as described above. Examplesof olefins of formula CH₂═CHR¹ that can be polymerized according to theprocess of the present invention are ethylene, propylene, 1-butene,1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene,4,6-dimethyl-1-heptene. Preferred olefins are ethylene, propylene,1-butene.

The present invention further provides polyolefins, and in particularpropylene (pre)polymers optionally containing from 0.1 to 20% by molesof units deriving from an olefin of formula CH₂═CHR⁴, R⁴ being hydrogen,a C₂–C₂₀-alkyl or a C₆–C₁₂-aryl group, in the form of sphericalparticles, characterized in that said polymers have a porosity ofgreater than 0.54 cc/g (determined by mercury absorption) and a maximumof the pore size distribution curve greater than 10 μm.

Preferably, the porosity (determined by mercury absorption) is greaterthan 0.6 cc/g.

Preferably, the maximum of the pore size distribution curve is greaterthan 20 μm.

Preferably, the units deriving from an olefin are selected from thegroup consisting of ethylene, 1-butene and styrene, which can beemployed either alone or in mixtures thereof.

Preferably the content by weight of units derived from CH₂═CHR⁴ is lessthan 15%, most preferably less than 10%.

The olefin polymers obtained according to the process of the presentinvention can be chosen in view of its further use. It can be apropylene homopolymer preferably a crystalline or semi-crystallinepropylene homopolymer having generally a high index of isotacticity. Theindex of isotacticity, expressed as mol % of isotactic pentads mmmm, isgenerally greater than 70, and can even reach values of greater than 90.Otherwise for particular applications a lower crystallinity ispreferred.

Particularly, when using stereospecific catalysts, it is possible toobtain crystalline porous propylene homopolymers and propylene-ethylenecopolymers. These polymers are characterized by very high porosityvalues, which render them very interesting for applications, such as theuse as porous polymeric support for further polymerization processes orfor the preparation of master-batches with pigments and/or othersuitable additives.

Moreover, the porous polymers of propylene according to the presentinvention being in the form of spherical particles are endowed with verygood morphological characteristics, such as high bulk density values,flowability and good mechanical resistance.

The average diameter of the polymeric particles is between 50 and 5000μm.

The bulk density of the porous polymers of propylene according to thepresent invention is very low. Generally the bulk density of theseporous polymers of propylene have values, which are inferior to 0.42g/cc, preferably inferior to 0.350 g/cc and can even reach values of0.26 g/cc.

The molecular weight of the porous polymers of propylene according tothe present invention can vary over a wide range. Generally theintrinsic viscosity of the porous polymers of propylene according to thepresent invention is greater than 0.5 dl/g and can reach values ofgreater than 2.0 dl/g or even higher.

The polymer obtainable from the process of the present invention can beadvantageously used as organic carrier for supporting a catalyst systemfor polymerizing alpha olefins of formula CH₂═CH¹, R¹ being hydrogen, aC₁–C₂₀-alkyl or a C₆–C₁₂-aryl group.

Therefore according to a still further aspect of the present invention asolid catalyst system is provided obtainable by contacting in any order:

-   i) a porous polymer obtained according to the process defined above;-   ii) a suitable catalyst component and-   iii) a suitable cocatalyst.

The reaction is preferably carried out in hydrocarbon solvents, such ashexane, heptane, toluene and the like at a temperature ranging from −20to 120° C., preferably from 20° C. to 60° C.

Preferably the suitable catalyst component is contacted with a suitablecocatalyst and the mixture is contacted with the porous supportdescribed under i).

The compounds ii) and iii) that are not adsorbed on the porous carriercan be removed by washing methods or filtration.

The suitable catalyst component is preferably selected from compounds ofa transition metal M selected from the Groups 3 to 10 of the PeriodicTable of the Elements (new IUPAC version); preferred compounds of atransition metal are selected from the group consisting of:

-   (a) Compounds of Ti or V not containing Metal-π bond such as TiCl₄,    TiCl₃ or Ti(OR²)_(f)X_(g-f), R² being a hydrocarbon radical    containing up to 15 carbon atoms or a —COR³ group, R³ being a    hydrocarbon radical containing up to 15 carbon atoms, X being a    halogen and f ranges from 1 to 4 and g is the valence of titanium;    or vanadium based compounds such as VCl₃, VCl₄, VOCl₃ and vanadyl    halides. Most preferably, TiCl₄ or TiCl₃ is used.-   (b) Compounds of transition metal M containing at least a M-π bond    having the general formula (I):    QL_(l)ZMX¹ _(p)  (I)    -   wherein Q is selected from substituted or unsubstituted        cyclopentadienyl radicals, which can carry one or more condensed        cycles, which can contain one or more heteroatoms belonging to        Groups 13–17 of the Periodic Table of the Elements to form for        instance indenyl, tetrahydroindenyl, fluorenyl,        octaidrofluorenyl, tetrahydrofluorenyl, indolyl, thiopenthyl,        dithiophenecyclopentadienyl radical that can be substituted;    -   Z has the same meaning of Q or it can also be ═NR⁶, —O—, —S— and        ═PR⁶, R⁶ being selected from hydrogen, a C₁–C₂₀-alkyl,        C₃–C₂₀-cycloallyl, C₂–C₂₀-alkenyl, C₆–C₂₀-aryl,C₇–C₂₀-alkylaryl        or C₇–C₂₀-arylalkyl radical which can contains one or more        heteroatoms belonging to Groups 13–17 of the Periodic Table of        the Elements;    -   L is a divalent bridge connecting the moieties Q and Z;        preferably L is selected from the group consisting of        C₁–C₂₀-allylidene, C₃–C₂₀-cycloallylidene, C₂–C₂₀-alkenylidene,        C₆–C₂₀-arylidene, C₇–C₂₀-alkylarylidene or C₇–C₂₀-aryalkylidene        radical which can contains one or more heteroatoms belonging to        Groups 13–17 of the Periodic Table of the Elements; more        preferably L is selected from the group consisting of CR⁸ ₂,        C₂R⁸ ₄, SiR⁸ ₂, Si₂R⁸ ₄ o CR⁸ ₂SiR⁸ ₂ wherein R⁸ is selected        from the group consisting of hydrogen, a C₁–C₂₀-alkyl,        C₃–C₂₀-cycloalkyl, C₂–C₂₀-alkenyl, C₆–C₂₀-aryl, C₇–C₂₀-alkylaryl        or C₇–C₂₀-aryalkyl radical which can contains one or more        heteroatoms belonging to groups 13–17 of the Periodic Table of        the Elements; preferably R⁸ is hydrogen, methyl, phenyl;    -   M is an atom of a transition metal M selected from the Groups 3        to 10 or the lanthamide or actinide groups of the Periodic Table        of the Elements (new IUPAC version); preferably M is selected        from the group consisting of Titanium, Zirconium and Hafnium;    -   X¹, same or different, is a ligand selected from hydrogen, a        halogen, R⁹, OR⁹, OSO₂CF₃, OCOR⁹, SR⁹, NR⁹ ₂ group, wherein R⁹        is selected from hydrogen, a C₁–C₂₀-alkyl, C₃–C₂₀-cycloalkyl,        C₂–C₂₀-alkenyl, C₆–C₂₀-aryl, C₇–C₂₀-alkylaryl or        C₇–C₂₀-arylalkyl radical, optionally containing one or more        heteroatoms belonging to Groups 13–17 of the Periodic Table of        the Elements;    -   p is an integer of from 0 to 3, preferably from 1 to 3, more        preferably p is 2, being equal to the oxidation state of the        metal M minus 2;    -   1 is 0 or 1;-   (c) late transition metal complex of formula (II) or (III):    L^(a)M^(a)X^(a) _(p′)X^(a)′_(s′)  (II)    L^(a)M^(a)A^(a)  (III)    -   wherein M^(a) is a metal belonging to Group 8, 9, 10 or 11 of        the Periodic Table of the Elements (new IUPAC notation);    -   L^(a) is a bidentate or tridentate ligand of formula (VI):

-   -   wherein:    -   B is a C₁–C₅₀ bridging group linking E¹ and E², optionally        containing one or more atoms belonging to Groups 13–17 of the        Periodic Table of the Elements;    -   E¹ and E², the same or different from each other, are elements        belonging to Group 15 or 16 of the Periodic Table of the Element        and are bonded to said metal M^(a);    -   the substituents R^(a1), the same or different from each other,        are selected from the group consisting of hydrogen, linear or        branched, saturated or unsaturated C₁–C₂₀ alkyl, C₁–C₂₀        alkyliden, C₃–C₂₀ cycloalkyl, C₆–C₂₀ aryl, C₇–C₂₀ alkylaryl and        C₇–C₂₀ arylalkyl radicals, optionally containing one or more        atoms belonging to Groups 13–17 of the Periodic Table of the        Elements (such as B, Al, Si, Ge, N, P, O, S, F and Cl atoms); or        two R^(a1) substituents attached to the same atom E¹ or E² form        a saturated, unsaturated or aromatic C₄–C₈ ring, having from 4        to 20 carbon atoms;    -   m′ and n′ are independently 0, 1 or 2, depending on the valence        of E¹ and E², so to satisfy the valence number of E¹ and E²; q′        is the charge of the bidentate or tridentate ligand so that the        oxidation state of M^(a)X^(a) _(p′)X^(a)′_(s′) or M^(a)A^(a) is        satisfied, and the compound (II) or (III) is overall neutral;    -   X^(a), the same or different from each other, are monoanionic        sigma ligands selected from the group consisting of hydrogen,        halogen, —R, —OR, —OSO₂CF₃, —OCOR, —SR, —NR₂ and —PR₂ groups,        wherein the R substituents are linear or branched, saturated or        unsaturated, C₁–C₂₀ alkyl, C₃–C₂₀ cycloalkyl, C₆–C₂₀ aryl,        C₇–C₂₀ alkylaryl or C₇–C₂₀ arylalkyl radicals, optionally        containing one or more atoms belonging to Groups 13–17 of the        Periodic Table of the Elements (new IUPAC notation), such as B,        N, P, Al, Si, Ge, O, S and F atoms; or two X^(a) groups form a        metallocycle ring containing from 3 to 20 carbon atoms; the        substituents X^(a) are preferably the same;    -   X^(a)′ is a coordinating ligand selected from mono-olefins and        neutral Lewis bases wherein the coordinating atom is N, P, O or        S;    -   p′ is an integer ranging from 0 to 3, so that the final        compound (II) or (III) is overall neutral;    -   s′ ranges from 0 to 3 and A^(a) is a π-allyl or a π-benzyl        group.

Compounds belonging to group (a) are usually used in conjunction with Mghalides and with one or more electron donors as described above.

Non-limiting examples of compounds of transition metal M containing aM-π bond are those described in WO 98/22486, WO 99/58539 WO 99/24446,U.S. Pat. No. 5,556,928, WO 96/22995, EP-485822 and EP-485820.

Non limiting examples of late transition metal complexes are thosedescribed in WO 96/23010, WO 97/02298, WO 98/40374 and J. Am. Chem. Soc.120:4049–4050, 1998.

The amount of the compound belonging to class (a) present in the porouspolymer according to the present invention can in generally reach valuesbetween 1×10⁻⁷ and 1×10⁻¹% by weight expressed as metal.

The amount of compounds of class (b) and class (c) present in the porouspolymer according to the present invention is generally between 1×10⁻⁷and 1×10⁻¹% by weight expressed as metal. The amount is preferablybetween 1×10⁻⁴ and 1×10⁻²% by weight.

The suitable co-catalyst can be Al-alkyl compounds as described above,alumoxanes or a compound able of forming an alkylmetallocene cation.Preferably Al-alkyl compounds are used with compounds belonging to class(a), while alumoxanes or a compound able of forming an allcylmetallocenecation are used with compounds belonging to class (b) and (c).

Alumoxanes can be obtained by reacting water with an organo-aluminumcompound of formula H_(j)AlR⁵ _(3-j) or H_(j)Al₂R⁵ _(6-j), where R⁵substituents, same or different, are hydrogen atoms, C₁–C₂₀-alkyl,C₃–C₂₀-cyclalkyl, C₆–C₂₀-aryl, C₇–C₂₀-alkylaryl or C₇–C₂₀-arylalkyl,optionally containg silicon or germanium atoms with the proviso that atleast one R⁵ is different from halogen, and j ranges from 0 to 1, beingalso a non-integer number. In this reaction the molar ratio of Al/wateris preferably comprised between 1:1 and 100:1.

The molar ratio between aluminum and the metal of the metallocene iscomprised between about 10:1 and about 20000:1, and more preferablybetween about 100:1 and about 5000:1.

The alumoxanes used in the catalyst according to the invention areconsidered to be linear, branched or cyclic compounds containing atleast one group of the type:

wherein the R⁵ substituents, same or different, are described above.

In particular, alumoxanes of the formula:

can be used in the case of linear compounds, wherein n is 0 or aninteger from 1 to 40 and the R¹⁵ substituents are defined as above, oralumoxanes of the formula:

can be used in the case of cyclic compounds, wherein n is an integerfrom 2 to 40 and the R⁵ substituents are defined as above.

Examples of alumoxanes suitable for use according to the presentinvention are methylalumoxane (MAO), tetra-(isobutyl)alumoxane (TIBAO),tetra-(2,4,4-trimethylpentyl)alumoxane (TIOAO),tetra-(2,3-dimethylbutyl)alumoxane (TDMBAO) andtetra-(2,3,3-trimethylbutyl)alumoxane (TTMBAO).

Particularly interesting cocatalysts are those described in WO 99/21899and in PCT/EP00/09111 in which the alkyl and aryl groups have specificbranched patterns.

Non-limiting examples of aluminum compounds according to said PCTapplications are:

-   tris(2,3,3-trimethyl-butyl)aluminum,    tris(2,3-dimethyl-hexyl)aluminum, tris(2,3-dimethylbutyl)aluminum,    tris(2,3-dimethyl-pentyl)aluminum,    tris(2,3-dimethyl-heptyl)aluminum,    tris(2-methyl-3-ethyl-pentyl)aluminum,    tris(2-methyl-3-ethyl-hexyl)aluminum,    tris(2-methyl-3-ethyl-hexyl)aluminum,    tris(2-methyl-3-propyl-heptyl)aluminum,    tris(2-ethyl-3-methyl-butyl)aluminum,    tris(2-ethyl-3-methyl-pentyl)aluminum,    tris(2,3-diethyl-pentyl)aluminum,    tris(2-propyl-3-methyl-butyl)aluminum,    tris(2-isopropyl-3-methyl-butyl)aluminum, tris(2- isobutyl-3-methyl    -pentyl)aluminum, tris(2,3,3-trimethyl-pentyl)aluminum,    tris(2,3,3-trimethylhexyl)aluminum,    tris(2-ethyl-3,3-dimethyl-butyl)aluminum,    tris(2-ethyl-3,3-dimethylpentyl)aluminumn,    tris(2-isopropyl-3,3-dimethyl-butyl)aluminum,    tris(2-trimethylsilylpropyl)aluminum,    tris(2-methyl-3-phenyl-butyl)aluminum,    tris(2-ethyl-3-phenylbutyl)aluminum,    tris(2,3-dimethyl-3-phenyl-butyl)aluminum,    tris(2-phenyl-propyl)aluminum,    tris[2-(4-fluoro-phenyl)-propyl]aluminum,    tris[2-(4-chloro-phenyl)-propyl]aluminumn, tris[2-(3    isopropyl-phenyl)-propyl]aluminum, tris(2-phenyl-butyl)aluminum,    tris(3-methyl-2-phenylbutyl)aluminum, tris(2-phenyl-pentyl)aluminum,    tris[2-(pentafluorophenyl)-propyl]aluminum,    tris[2,2-diphenyl-ethyl]aluminum and    tris[2-phenyl-2-methyl-propyl]aluminum, as well as the corresponding    compounds wherein one of the hydrocarbyl groups is replaced by an    hydrogen atom, and those wherein one or two of the hydrocarbyl    groups are replaced by an isobutyl group.

Amongst the above aluminum compounds, trimethylalumnum (TMA),triisobutylaluminum (TIBAL), tris(2,4,4-trimethyl-pentyl)aluminum(TIOA), tris(2,3-dimethylbutyl)aluminum (TDMBA) andtris(2,3,3-trimethylbutyl)aluminum (TTMBA) are preferred.

The molar ratio between the aluminum and the metal of the metallocenecompound is in general comprised between 10:1 and 20000:1, andpreferably between 100:1 and 5000:1.

Non-limiting examples of compounds able to form an alkylmetallocenecation are compounds of formula D⁺E⁻, wherein D⁺ is a Brønsted acid,able to give a proton and to react irreversibly with a non π substituentof the metallocene compound and E⁻ is a compatible anion, which is ableto stabilize the active catalytic species originating from the reactionof the two compounds, and which is sufficiently labile to be able to beremoved by an olefinic monomer. Preferably, the anion E⁻ consists of oneor more boron atoms. More preferably, the anion E⁻ is an anion offormula BAr₄ ⁽⁻⁾, wherein the substituents Ar which can be identical ordifferent are aryl radicals such as phenyl, pentafluorophenyl orbis(trfluoromethyl)phenyl. Tetrakis-pentafluorophenyl borate isparticularly preferred. Moreover, compounds of formula BAr₃ canconveniently be used. Compounds of this type are described, for example,in the published International patent application WO 92/00333, thecontent of which is incorporated in the present description.

Further, compounds of formula R⁷M¹—O—M¹R⁷, R⁷ being an alkyl or arylgroup, and M¹ is selected from an element of the Group 13 of thePeriodic Table of the Elements (new IUPAC version). Compounds of thistype are described, for example, in the International patent applicationWO 99/40129.

The metallocene compounds (class (b)) or late transition metal complexes(class (c)) can be supported by using solution thereof in a hydrocarbonsolvent, such as hexane, benzene, toluene and the like. This solutioncan also contain a co-catalyst, for instance, a trialkyl-Al compound,such as triisobutyl-Al, triethyl-Al and/or polyaluminoxane such asmethylalumoxane. The molar ratio between the alkyl-Al compound and themetallocene compound is generally greater than 2 and preferably between5 and 5000, more preferably between 5 and 1000.

Preferably, the cocatalyst is alumoxane and/or a compound capable offorming an alkyl metallocene cation.

The process of the present invention can be also used as first step of amultistep process such as that described in WO 96/11218, WO 96/2583, WO00/11057 and WO 00/53646. In this process the polymer prepared accordingto the process of the present invention is impregnated with ametallocene compound or a late transition metal complex and with asuitable co-catalyst as defined above and then one or more olefins arepolymerized. The polymer of the first steps range from 10% to 70% byweight of the total polymer obtained in the multistep process,preferably from 10% to 60% by weight, more preferably from 20% to 50% byweight.

Thus, a still further aspect of the present invention is a process forthe polymerization of one or more olefins of formula CH₂═CHR¹, R¹ beinghydrogen, a C₁–C₂₀-allyl or a C₆–₁₂-aryl group, comprising the followingsteps:

-   (A) polymerizing said olefin CH₂═CHR¹, in one or more reactors,    according to the process of the present invention, in order to    obtain a porous polymeric polymer as defined above;-   (B) optionally deactivating the catalyst used under (A) and    contacting the product as obtained under step (A) with a suitable    catalyst component selected from the groups (a), (b) or (c)    described above and optionally an Al-alkyl compound or an alumoxane    or a compound capable of forming an alkyl metallocene cation;-   (C) polymerizing one or more of said olefins CH₂═CHR¹, in one or    more reactors, in the presence of the product obtained in step (B).

Preferably in step (B) compounds selected from group (b) or (c) areused. Preferably in step (B) the catalyst used under (A) is deactivated.

The highly porous polymers obtained in above step (A) are particularlyuseful as porous polymeric support containing a significant amount of asecond catalyst system as described in above step (B). The thus obtainedpolymeric porous support is particularly useful in the subsequentpolymerization stage (C). A particular advantage of the highly porouspolymers of the present invention is their use in the preparation ofrubber-like copolymers. The high porosity of said porous polymers asprepared in step (A) makes it possible to work in the gas phase withoutparticular problems, favoring good activities together with low fouling.

The amount of the highly porous polymer according to the presentinvention in step (A) is generally greater than 2000 g/g of solidcomponent, preferably greater than 3000 g/g, and more preferably greaterthan 5000 g/g.

Preferably, the solid component used in step (A) is in the form ofspherical particles having an average diameter of between 10 and 150 μm.

Preferably, in the product obtained from step (B), the compound selectedfrom the groups (a), (b) or (c) is present in a quantity of between1×10⁻⁷ and 1×10⁻³% by weight expressed as metal.

The deactivating step, if any, of the catalyst used in (A) prior to thecontact treatment with the metallocene is carried out with a compoundthat is capable of deactivating the catalyst present in the productobtained in step (A).

Preferably the compound that is capable of deactivating the catalyst isselected from the group consisting of CO, COS, CS₂, CO₂, O₂, acetyleniccompounds, allenic compounds and compounds of general formula R¹⁰_(y-1)X²H in which R¹⁰ is hydrogen or a hydrocarbon group with from 1 to10 carbon atoms, X² is oxygen, nitrogen or sulfur and y is the valenceof X².

Non-limiting examples of compounds for use as a deactivating agent canbe found in U.S. Pat. No. 5,648,422, the disclosure of which beingincorporated herein by reference.

Preferably, the step (A) is carried out in liquid phase in the presenceof an organic solvent or in gas phase and the step (C) is carried out inthe gas phase in at least one reactor with a fluidized bed or amechanically-stirred bed.

More preferably, both steps (A) and (C) are carried out in the gas phasewith a fluidized bed or a mechanically stirred bed.

Preferably, the step (B) is carried out in the gas phase.

The process of the invention can be used for a wide range of olefinpolymer compositions. The process of the invention is particularlysuitable for the preparation of heterophase copolymers of propylene,from high-impact polypropylene to thermoplastic elastomers.

Thus, a still further aspect of the present invention is a process forthe preparation of heterophase copolymers of propylene comprising thefollowing steps:

-   (A) polymerizing, in at least one reactor, propylene or its mixtures    with one or more olefins CH₂═CHR⁴, R⁴ being hydrogen, a C₂–C₂₀-alkyl    or a C₆–C₁₂-aryl group, according to the process of the present    invention, said polymer having a content of units derived from the    ethylene or the olefin of less than 20% by weight and a content of    units derived from the propylene of greater than 80% by weight;-   (B) optionally deactivating the catalyst used under (A) and    contacting the product as obtained under step (A) with a compound    selected from the groups (a), (b) or (c) described above and    optionally an Al-alkyl compound or an alumoxane or a compound    capable of forming an alkyl metallocene cation;-   (C) polymerizing, in at least one reactor at least two olefins    selected from those belonging to formula CH₂═CHR¹, R¹ being    described above and optionally a polyene, in the presence of a    product obtained under step (B).

The polymer produced in step (A) is preferably a highly poroushomopolymer of propylene having high isotacticity or a highly copolymerof propylene having a content by weight of units derived from ethyleneand/or from an olefin CH₂═CHR⁴, R⁴ being defined as above, less than 10%by mol.

Non-limiting examples of copolymers obtained in step (C) of the processof the present invention are elastomeric copolymers of ethylene andpropylene i.e. ethylene and propylene monomers are polymerized orelastomeric terpolymers of ethylene and propylene containing minoramounts of polyene i.e. ethylene, propylene and a polyene monomers arepolymerized. The polyenes that can be used as comonomers in thecopolymers according to the present invention are comprised in thefollowing classes:

-   -   non-conjugated diolefins able to cyclopolymerize such as, for        example, 1,5-hexadiene, 1-6-heptadiene, 2-methyl-1,5-hexadiene;    -   dienes capable of giving unsaturated monomeric units, in        particular conjugated dienes such as, for example, butadiene and        isoprene, and linear non-conjugated dienes, such as, for        example, trans 1,4-hexadiene, cis 1,4-hexadiene,        6-methyl-1,5-heptadiene, 3,7-dimethyl-1,6-octadiene,        11-methyl-1,10-dodecadiene, and cyclic non-conjugated dienes        such as 5-ethylidene-2-norbornene.

A preferred polyene for use in the copolymers of the invention is5-ethylidene-2-norbornene (ENB).

The content of units derived from ethylene is between about 20 and 80%by mol, preferably 30 and 70% by mol. The content of polyene derivedunits, if any, is preferably comprised between 0.1% and 30% by mol and,more preferably between 0.1% and 20% by mol.

The polymers obtained in step (C) of the process of the presentinvention can be substantially amorphous, elastomeric, flexible orcrystalline.

A particular advantage of porous polymer according to the presentinvention is that a very high amount of elastomeric copolymer obtainedin above step (C) of the process according to the present invention canbe combined with said porous polymer of step (A), without incurringmajor problems in the polymerization process, such as fouling. Thus, theamount of the polymer produced in stage (C) is preferably between 10%and 90%, more preferably between 50% and 80%, relative to the amount ofpolymer produced in stage (A).

A further advantage, alongside to the very good processability, of theprocess according to the present invention is that the use of the porouspolymers enables the preparation of polymeric compositions in very goodyield and enhanced quality.

Preferably the olefin used as comonomer in step (C) is selected fromethylene, 1-butene, styrene.

The process of the present invention is preferably carried out incontinuos mode. Both polymerization steps described in (A) and (C) arepreferably carried out in the gas phase in the presence of afluidized-bed reactor, treatment step (B) being carried out in the gasphase.

The polymerization step (C) can also be carried out in suspension, insolution, emulsion or in gas-phase with a mechanically stirred bed. Thefirst polymerization stage (A) is preferably carried out such that aprepolymer of propylene or its mixtures with ethylene and/or an olefinCH₂═CHR¹, R¹ being defined as above, is formed in the presence of thecatalyst as mentioned in above step (A). The prepolymer is generallyformed in a quantity of between 5 and 5000 g/g of catalyst. Theprepolymerization can be carried out in liquid propylene in the presenceof an inert hydrocarbon solvent, such as hexane or benzene.

The advantages of the process according to the present invention arefound both in the quality of the final product and in the flexibility ofthe process.

When the porous polymer obtained according to the present invention isused as support or when the process of the present invention is used asfirst step of a multi-step process as above described it is possible toenhance both the characteristic of the process and the feature of thefinal polymer obtained. The enhanced porosity of the polymer of thepresent invention permits to obtain supported or impregnated catalystsystem with high activity. Moreover it is possible to reduce the foulingof the process when the polymer of the present invention is used assupport enhancing at the same time the morphology of the final polymer.

The following examples are given solely for illustrative purpose and arenot intended to limit the scope of the present invention.

General Procedures

The data reported in the Examples relative to the properties of theporous polymers of the present invention were determined according tothe methods indicated below.

MIL flow index: ASTM-D1238.

Intrinsic viscosity (I.V.): measured in tetrahydronaphtalene (THN) at135° C.

Fraction soluble in xylene: 2 g of polymer were dissolved in 250 ml ofxylene at 135° C. under stirring. After 20 minutes the solution was leftto cool, still under stirring, up to 25° C. After 30 minutes theprecipitated material was filtered through filter paper, the solutionwas evaporated in nitrogen current and the residual was dried undervacuum at 80° C. until it reached constant weight. Thus, the percentageof polymer soluble in xylene at room temperature was calculated.

Porosity (mercury) is determined by immersing a known quantity of thesample in a known quantity of mercury inside a dilatometer and graduallyhydraulically increasing the pressure of the mercury. The pressure ofintroduction of the mercury in the pores is in function of the diameterof the same. The measurement was carried out using a porosimeter“Porosimeter 2000 Series” (Carlo Erba). The total porosity wascalculated from the volume decrease of the mercury and the values of thepressure applied.

The porosity expressed as percentage of voids is determined byabsorption of mercury under pressure. The volume of mercury absorbedcorresponds to the volume of the pores. For this determination, acalibrated dilatometer (diameter 3 mm) CD3 (Carlo Erba) connected to areservoir of mercury and to a high-vacuum pump (1×10⁻² mbar) is used. Aweighed amoumt of sample (about 0.5 g) is placed in the dilatometer. Theapparatus is then placed under high vacuum (<0.1 mm Hg) and ismaintained in these conditions for 10 minutes. The dilatometer is thenconnected to the mercury reservoir and the mercury is allowed to flowslowly into it until it reaches the level marked on the dilatometer at aheight of 10 cm. The valve that connects the dilatometer to the vacuumpump is closed and the apparatus is pressurized with nitrogen (2.5Kg/cm²). Under the effect of the pressure, the mercury penetrates intothe pores and the level goes down according to the porosity of thematerial. Once the level at which the mercury has stabilized has beenmeasured on the dilatometer, the volume of the pores is calculated fromthe equation V═R2πΔH, where R is the radius of the dilatometer and ΔH isthe difference in cm between the initial and the final levels of themercury in the dilatometer. By weighting the dilatometer,dilatometer+mercury, dilatometer+mercury+sample, the value of theapparent volume V₁ of the sample prior to penetration of the pores canbe calculated.

The volume of the sample is given by:V ₁ =[P ₁−(P ₂ −P)]/DP is the weight of the sample in grams, P₁ is the weight of thedilameter+mercury in grams, P₂ is the weight of thedilatometer+mercury+sample in grams, D is the density of mercury (at 25°C.=13.546 g/cc). The percentage porosity is given by the relation:X=(100V)V ₁.

The pore distribution curve, and the average pore size are directlycalculated from the integral pore distribution curve which is functionof the volume reduction of the mercury and applied pressure values (allthese data are provided and elaborated by the porosimeter associatedcomputer which is equipped with a “MILESTONE 200/2.04” program by C.Erba.

Bulk density: DIN-53194.

Morphology: ASTM-D1921-63.

EXAMPLES

Preparation of MgCl₂/alcohol Adducts

The MgCl₂/alcohol adducts in spherical particle form were preparedfollowing the method described in Example 2 of U.S. Pat. No. 4,399,054,but operating at 5,000 rpm instead of 10,000 rpm. The adduct waspartially dealcoholated by heating at temperatures from 50° to 100° C.,under a nitrogen stream until the desired alcohol content was obtainedaccording to the description of EP 0 395 083.

Preparation of the Catalysts

The catalyst used in Examples 1 to 6 were prepared following the generalmethod described in EP 0 395 083 by using an adduct with a content ofalcohol of 50% wt for the catalyst used in Examples 1 and 2, and 35% wtfor the catalyst used in Examples 3 to 6.

Example 1 (Comparative Example)

A MgCl₂.3C₂H₅OH adduct in spherical particle form which particles have adiameter from 30 to 150 microns was prepared following the methoddescribed in Example 2 of U.S. Pat. No. 4,399,054, the disclosure ofsaid method being incorporated herein by reference, operating at 5,000rpm instead of 10,000 rpm. The resultant adduct is then dealcoholated byheating with temperatures increasing from 50° to 100° C., under anitrogen stream until the alcohol content reaches 50 wt %.

The solid obtained was used in order to prepare the catalyst followingthe procedure described in EP 0 395 083.

The polymerisation reaction was carried out following the proceduredescribed in EP 0 395 083 as follows.

Using 0.011 g of the solid component, a propylene polymerisation wascarried out in a 4 l autoclave equipped with magnetically driven stirrerand a thermostatic system, previously fluxed with nitrogen at 70° C. forone hour and then with propylene. Into the reactor at 30° C., withoutstirring but under propylene stream, a catalyst system consisting of asuspension of the solid component in 15 ml of hexane, 1.14 g oftriethylaluminum, and 114 mg of dicyclopentyldimethoxysilane isintroduced, this system is prepared just prior to its use in thepolymerisation test.

The autoclave is then closed and 3.5 l of hydrogen are introduced. Understirring, 1.3 Kg of propylene was charged and the temperature wasbrought to 70° C. in 5 minutes, maintaining the value constant for twohours. At the end of the test, the stirring was stopped and theunreacted propylene was vented off. After cooling the autoclave to roomtemperature, the polymer is recovered and then dried at 70° C. under anitrogen stream in an oven for 3 hours. 560 g of spherical polymer areobtained having the following characteristics:

-   fraction soluble in xylene=1.5%-   I.V.=2.02 dl/g-   Bulk density=0.466 g/cc-   Void percentage=10.2

The characteristics of the obtained polymer are reported in Table 1.

Example 2

The autoclave of Example 1 was equipped with a 50-ml stainless steelvial connected on the bottom of the reactor. The autoclave was closed inpropylene atmosphere and 3 l of hydrogen and 1300 g of propylene wasintroduced under stirring. The temperature was raised at 50° C., and anhexane suspension of the catalyst system containing 0.0095 g of thecatalyst component of Example 1 and the others ingredients as describedin Example 1, were injected, under nitrogen pressure and through thestainless steel vial, into the autoclave. The temperature was keptconstant at 50° C. for 5 minutes, then was raised at 70° C. in 5minutes.

The polymerization is carried out at the same temperature for a totalperiod of time of 2 hours.

Then according to the procedure of Example 1, 390 g of a sphericalpolymer are obtained, having the following characteristics:

-   fraction soluble in xylene=1.8%-   I.V.=2.10 dl/g-   Bulk density=0.418 g/cc-   Void percentage=19.2

The characteristics of the obtained polymer are reported in Table 1.

Example 3 (Comparative Example)

According to the above Example 1 a catalyst component in spherical formwas prepared by partially dealcoholising a MgCl₂.3EtOH adduct, until aresidual content of 35 wt % was obtained. Using 0.019 g of this catalystcomponent in the propylene polymerisation according to the procedure ofExample 1 (3 l of hydrogen instead of 3.5 l were used), 418 g ofspherical polymer are obtained having the following characteristics:

-   fraction soluble in xylene=3.4%-   I.V.=1.9 dl/g-   Bulk density=0.350 g/cc-   Void percentage=32.6

The characteristics of the obtained polymer are reported in Table 1.

Example 4

Using 0.022 g of the catalyst component of Example 3, and according tothe ingredients and the propylene polymerization procedure of Example 1,except that for the time requested to raise the temperature of theautoclave, i.e. from 30° C. to 70° C., were 2 minutes, instead of 5minutes. 440 g of spherical polymer were obtained having the followingcharacteristics:

-   fraction soluble in xylene=3.5%-   I.V.=1.68 dl/g-   Bulk density=0.288 g/cc-   Void percentage=35.1

The characteristics of the obtained polymer are reported in Table 1.

Example 5

Using 0.02 g of the catalyst component of Example 3, and according tothe ingredients and the propylene polymerization procedure of Example 2(but for the amount of hydrogen reduced at 2.5 l) and injecting thecatalytic suspension at 55° C., instead of 50° C., and then keeping thetemperature constant at 55° C. for 5 minutes, 280 g of spherical polymerwere obtained having the following characteristics:

-   fraction soluble in xylene=3.6 wt %-   I.V.=1.47 dl/g-   Bulk density=0.261 g/cc-   Void percentage=39.5

The characteristics of the obtained polymer are reported in Table 1.

Example 6

The autoclave of Example 1 was equipped with a 50-ml stainless steelvial connected on the bottom of the reactor and the stirring wasprovided by a custom ribbon type stirrer and variable speed. Theautoclave was closed in propylene atmosphere and 3.3 l of hydrogen and600 g of propylene are introduced, under stirring at 600 rpm. Then thetemperature was raised at 50° C., and 15 ml of an hexane suspension ofthe catalyst system containing 0.045 g of catalyst component of Example3, 0.912 g of triethylaluminum and 182 mg ofdicyclopentyldimethoxysilane, were injected, under nitrogen pressure,into the autoclave by the stainless steel vial.

The temperature was kept constant at 50° C. for 5 minutes, then thestirring was stopped and the unreacted propylene was vented off. As aconsequence, the temperature decreased at 30° C. Then, under stirring at300 rpm, 207 g of propylene were introduced into the reactor in 8minutes and, at the same time, the temperature was raised at 75° C. and3.4 l of hydrogen, were charged by a pressurized cylinder. Thetemperature was kept constant and in order to maintain constant thepressure at 24 bar-g, 220 g of propylene were fed during apolymerization time of 30 minutes.

The stirring was stopped and the autoclave was vented and cooled at roomtemperature. 328 g of a spherical polymer were obtained having thefollowing characteristics:

-   fraction soluble in xylene=3.10 wt %-   I.V.=1.81 dl/g-   Bulk density=0.264 g/cc-   Void percentage=41.6

The characteristics of the obtained polymer are reported in Table 1.

Example 7 (Comparative Example)

A catalyst component was prepared according to the procedure asdescribed in Example 1 of U.S. Pat. No. 4,220,554, except that, insteadof benzoyl chloride, diisobutylphthalate (DIBP) was used. Using 0.009 gof this catalyst component in the propylene polymerisation according tothe procedure and the ingredients of Example 1, 330 g of granularpolymer (flakes) were obtained having the following characteristics:

-   fraction soluble in xylene=1.4%-   I.V.=1.95 dl/g-   Bulk density=0.499 g/cc-   Void percentage=8.7

The characteristics of the obtained polymer are reported in Table 1.

Example 8

Using 0.019 g of the catalyst component of Example 7 and according tothe ingredients and the propylene polymerization procedure of Example 5and injecting the catalytic suspension at 55° C. and then keeping thetemperature constant at 55° C. for 5 minutes, 280 g of granular polymer(flakes) were obtained having the following characteristics:

-   fraction soluble in xylene=1.5 wt %-   I.V.=2.1 dl/g-   Bulk density=0,400 g/cc-   Void percentage=18.8

The characteristics of the obtained polymer are reported in Table 1.

Example 9

The example 5 was repeated, except that 0.031 g of the catalystcomponent and ethylene and propylene were used.

1.3 kg of propylene and 26 g of ethylene and 3 l of hydrogen wereintroduced into the reactor. The catalytic components were injected intothe reaction medium heated at 50° C. The temperature was kept constantfor 5 minutes, then raised at 70° C. and kept constant for 39 minuteswhile feeding 30 g of ethylene, in order to maintain a constant pressureof 31 bar-g. 216 g of copolymer were obtained having the followingcharacteristics:

-   I.V.=2.5 dl/g-   Ethylene content=8.6 wt %-   Bulk density=0.250 g/cc-   Void percentage=27.9

The characteristics of the obtained polymer are reported in Table 1.

TABLE 1 Bulk Surface Pore Porosity Average P.S.D. Catalyst PP I.V.density Area volume in % of radlus (μm; peak Ex mg g dl/g g/cc m²/g cc/gvoids μm maximum) 1# 11 560 2.02 0.466 0.1 0.131 10.2 10.9 n.a. 2 9.5390 2.10 0.418 0.4 0.265 19.2 12.4 n.a. 3# 19 418 1.9 0.350 0.7 0.53832.6 8.7 6.8 4 22 440 1.68 0.288 0.4 0.668 35.1 14.9 27 5 20 280 1.470.261 0.3 0.763 39.5 15.9 38 6 45 328 1.81 0.264 0.5 0.853 41.6 14.1 307# 9 330 1.95 0.499 0.2 0.107 8.7 24.9 n.a. 8 19 280 2.1 0.400 0.2 0.25618.8 19.0 n.a. 9 31  216* 2.5 0.250 1.0 0.464 27.9 19.5 n.a. P.S.D.:pore size distribution n.a.: not available *propylene-ethylene copolymer#comparative

1. A process for preparing porous olefin polymers, having a porosity ofgreater than 0.54 cc/g, comprising putting into contact in apolymerization reactor having a reactor temperature initially at atemperature T¹, one or more olefins of formula CH₂═CHR¹, R¹ beinghydrogen, a C₁–C₂₀-alkyl or a C₆–C₁₂-aryl group with a catalyst obtainedby reacting a solid catalyst component in the form of spheroidalparticles comprising a compound of Ti or V not containing metal -π bondsand a Mg halide, optionally containing one or more electron donorcompounds, with an aluminum-alkyl (Al-alkyl) compound, then raising thereactor temperature up to a polymerization temperature, wherein (I) ifthe temperature T¹ is lower than 40° C., the reactor temperature israised up to the polymerization temperature in such a way that, for atime of at least one minute after the introduction of the catalystsystem into the reactor, the reactor temperature is raised up to T²under the following condition: $\frac{T^{2} - T^{1}}{m} > 10$  wherein mis the time, expressed in minutes, employed for reaching the temperatureT²; or (II) if the temperature T¹ is 40° C. or higher, the reactortemperature is maintained for a time of at least one minute at atemperature ranging from 45° C. to 65° C., wherein the process producesat least about 500 grams of the porous olefin polymers per gram of thesolid catalyst component.
 2. The process according to claim 1 wherein T¹ranges from 28° C. to the polymerization temperature.
 3. The processaccording to claim 1 wherein m is between 1 and 5 minutes.
 4. Theprocess according to claim 1 wherein polymerization is carried out at atemperature ranging generally between 40° and 150° C.
 5. The process ofclaim 1 wherein under (II) the reactor temperature is maintained for atime of between 1 and 5 minutes at a temperature ranging from 45° C. to65° C.
 6. A solid catalyst system obtained by contacting in any order:(A) a porous polymer, having a porosity of greater than 0.54 cc/g,obtained in a process comprising putting into contact in apolymerization reactor having a reactor temperature initially at atemperature T¹, one or more olef ins of formula CH₂═CHR¹, R¹ beinghydrogen, a C₁–C₂₀-alkyl or a C₆–C₁₂-aryl group with a catalyst obtainedby reacting the solid catalyst component in the form of spheroidalparticles comprising a compound of Ti or V not containing metal-π bondsand a Mg halide, optionally containing one or more electron donorcompounds, with an aluminum-alkyl (Al-alkyl) compound, then raising thereactor temperature up to a polymerization temperature, wherein (I) ifthe temperature T¹ is lower than 40° C., the reactor temperature israised up to the polymerization temperature in such a way that, for atime of at least one minute after the introduction of the catalystsystem into the reactor, the reactor temperature is raised up to T₂under the following condition: $\frac{T^{2} - T^{1}}{m} > 10$  wherein mis the time, expressed in minutes, employed for reaching the temperatureT²; or (II) if the temperature T¹ is 40° C. or higher, the reactor ismaintained for a time of at least one minute at a temperature rangingfrom 45° C. to 65° C.; (B) a suitable catalyst component; and (C) asuitable cocatalyst, wherein the solid catalyst system produces theporous polymer in a ratio of at least about one gram to about 500 grams.7. The solid catalyst system according to claim 6 wherein the suitablecatalyst component is selected from compounds of a transition metal Mselected from the Groups 3 to 10 of the Periodic Table of the Elements(new IUPAC version).
 8. The solid catalyst system according to claim 7wherein the suitable catalyst component is selected from the groupconsisting of: (a) compounds of Ti or V not containing a metal-π bond;(b) compounds of transition metal M containing at least a M-π bondhaving a general formula (I)QL_(l)ZMX¹ _(p)   (I) wherein Q is selected from substituted orunsubstituted cyclopentadienyl radicals, which can carry one or morecondensed cycles, which can contain one or more heteroatoms belonging toGroups 13–17 of the Periodic Table of the Elements; Z has the samemeaning of Q or it can also be ═NR⁶, —O—, —S— and ═PR⁶, R⁶ beingselected from hydrogen, a C₁–C₂₀-alkyl, C₃–C₂₀-cycloalkyl,C₂–C₂₀-alkenyl, C₆–C₂₀-aryl, C₇–C₂₀-alkylaryl or C₇–C₂₀-arylalkylradical which can contain one or more heteroatoms belonging to Groups 13–17 of the Periodic Table of the Elements; L is a divalent bridgeconnecting the moieties Q and Z; M is an atom of transition metalselected from the Groups 3 to 10 or the lanthanide or actinide groups ofthe Periodic Table of the Elements (new TUPAC version); X¹, same ordifferent, is a ligand selected from hydrogen, a halogen, R⁹, OR⁹,OSO₂CF₃, OCOR⁹, SR⁹, NR⁹ ₂ or PR⁹ ₂ group, wherein R⁹ is selected fromhydrogen, a C₁–C₂₀-alkyl, C₃–C₂₀-cycloalkyl, C₂–C₂₀-alkenyl,C₆–C₂₀-aryl, C₇–C₂₀-alkylaryl or C₇–C₂₀-arylalkyl radical, optionallycontaining one or more heteroatoms belonging to Groups 13–17 of thePeriodic Table of the Elements; p is an integer of from 0 to 3; 1 is 0or 1; and (c) a late transition metal complex of formula (II) or (III):L^(a)M^(a)X^(a) _(p′)X^(a′) _(s′)  (II)L^(a)M^(a)A^(a)   (III) wherein M^(a) is a metal belonging to Group 8,9, 10 or 11 of the Periodic Table of the Elements (new IUPAC notation);L^(a) is a bidentate or tridentate ligand of formula (VI):

wherein: B is a C₁–C₅₀ bridging group linking E¹ and E², optionallycontaining one or more atoms belonging to Groups 13–17 of the PeriodicTable; E¹ and E², the same or different from each other, are elementsbelonging to Group 15 or 16 of the Periodic Table and are bonded to saidmetal M^(a); the substituents R^(a1), the same or different from eachother, are selected from the group consisting of hydrogen, linear orbranched, saturated or unsaturated C₁–C₂₀ alkyl, C₁–C₂₀ alkyliden,C₃–C₂₀ cycloalkyl, C₆–C₂₀ aryl, C₇–C₂₀ alkylaryl and C₇–C₂₀ arylalkylradicals, optionally containing one or more atoms belonging to Groups13–17 of the Periodic Table of the Elements; or two R^(a1) substituentsattached to the same atom E¹ or E² form a saturated, unsaturated oraromatic C₄–C₈ ring, having from 4 to 20 carbon atoms; m′ and n′ areindependently 0, 1 or 2, depending on the valence of E¹ and E², so tosatisfy the valence number of E¹ and E²; q′ is the charge of thebidentate or tridentate ligand so that the oxidation state of M^(a)X^(a)_(p)X^(a)′_(s) or M^(a)A^(a) is satisfied, and the compound (II) or(III) is overall neutral; X^(a), the same or different from each other,are monoanionic sigma ligands selected from the group consisting ofhydrogen, halogen, —R, —OR, —OSO₂CF₃, —OCOR, —SR, —NR₂ and —PR₂ groups,wherein the R substituents are linear or branched, saturated orunsaturated, C₁–C₂₀ alkyl, C₃–C₂₀ cycloalkyl, C₆–C₂₀ aryl, C₇–C₂₀alkylaryl or C₇–C₂₀ arylalkyl radicals, optionally containing one ormore atoms belonging to Groups 13–17 of the Periodic Table of theElements (new IUPAC notation), or two X^(a) groups form a metallocyclering containing from 3 to 20 carbon atoms; X^(a)′ is a coordinatingligand selected from mono-olefins and neutral Lewis bases wherein thecoordinating atom is N, P, O or S; p′ is an integer ranging from 0 to 3,so that the final compound (II) or (III) is overall neutral; s′ rangesfrom 0 to 3; and A^(a) is a π-allyl or a π-benzyl group.
 9. The solidcatalyst system according to claim 6 wherein the suitable co-catalystcomprises at least one of Al-alkyl compounds, alumoxanes and a compoundthat forms an alkylmetallocene cation.
 10. A process for polymerizationof one or more olef ins of formula CH₂═CHR¹, R¹ being hydrogen, aC₁–C₂₀-alkyl or a C₆–C₁₂-aryl group, comprising the following steps: (A)polymerizing said olefin CH₂═CHR¹, in one or more reactors, by a processcomprising putting into contact in a polymerization reactor having areactor temperature initially at a temperature T¹, one or more olef insof formula CH₂═CHR¹, R¹ being hydrogen, a C₁–C₂₀-alkyl or a C₆–C₁₂-arylgroup with a catalyst obtained by reacting a solid catalyst component inthe form of spheroidal particles comprising a compound of Ti or V notcontaining metal-π bonds and a Mg halide, optionally containing one ormore electron donor compounds, with an aluminum-alkyl (Al-alkyl)compound, then raising the reactor temperature up to a polymerizationtemperature, wherein (I) if the temperature T¹ is lower than 40° C., thereactor temperature is raised up to the polymerization temperature insuch a way that, for a time of at least one minute after theintroduction of the catalyst system into the reactor, the reactortemperature is raised up to T² under the following condition:$\frac{T^{2} - T^{1}}{m} > 10$  wherein m is the time, expressed inminutes, employed for reaching the temperature T²; or (II) if thetemperature T¹ is 40° C. or higher, the reactor is maintained for a timeof at least one minute at a temperature ranging from 45° C. to 65° C.;(B) optionally deactivating the catalyst used under (A) and contactingthe product as obtained under step (A) with a catalyst componentselected from the group consisting of: (a) compounds of Ti or V notcontaining a metal-π bond; (b) compounds of transition metal Mcontaining at least a M-π bond having a general formula (I):QL_(l)ZMX¹ _(p)   (I) wherein Q is selected from substituted orunsubstituted cyclopentadienyl radicals, which can carry one or morecondensed cycles, which can contain one or more heteroatoms belonging toGroups 13–17 of the Periodic Table of the Elements; Z has the samemeaning of Q or it can also be ═NR⁶, —O—, —S— and ═PR⁶, R⁶ beingselected from hydrogen, a C₁–C₂₀-alkyl, C₃–C₂₀-cycloalkyl,C₂–C₂₀-alkenyl, C₆–C₂₀-aryl, C₇–C₂₀-alkylaryl or C₇–C₂₀-arylalkylradical which can contain one or more heteroatoms belonging to Groups13–17 of the Periodic Table of the Elements; L is a divalent bridgeconnecting the moieties Q and Z; M is an atom of transition metalselected from the Groups 3 to 10 or the lanthanide or actinide groups ofthe Periodic Table of the Elements (new IUPAC version); X¹ same ordifferent, is a ligand selected from hydrogen, a halogen, R⁹, OR⁹,OSO₂CF₃, OCOR⁹, SR⁹, NR⁹ ₂ or PR⁹ ₂ group, wherein R⁹ is selected fromhydrogen, a C₁–C₂₀ -alkyl, C₃–C₂₀-cycloalkyl, C₂–C₂₀-alkenyl,C₆–C₂₀-aryl, C₇–C₂₀-alkylaryl or C₇–C₂₀-arylalkyl radical, optionallycontaining one or more heteroatoms belonging to Groups 13–17 of thePeriodic Table of the Elements; p is an integer of from 0 to 3; 1 is 0or 1; and (c) a late transition metal complex of formula (II) or (III):L^(a)M^(a)X^(a) _(p′)X^(a) ^(′) _(s′)  (II)L^(a)M^(a)A^(a)   (III) wherein M^(a) is a metal belonging to Group 8,9, 10 or 11 of the Periodic Table of the Elements (new IUPAC notation);L^(a) is a bidentate or tridentate ligand of formula (VI):

wherein: B is a C₁–C₅₀ bridging group linking E¹ and E^(2,) optionallycontaining one or more atoms belonging to Groups 13–17 of the PeriodicTable; E¹ and E², the same or different from each other, are elementsbelonging to Group 15 or 16 of the Periodic Table and are bonded to saidmetal M^(a); the substituents R^(a1), the same or different from eachother, are selected from the group consisting of hydrogen, linear orbranched, saturated or unsaturated C₁–C₂₀ alkyl, C₁–C₂₀ alkyliden,C₃–C₂₀ cycloalkyl, C₆–C₂₀ aryl, C₇–C₂₀ alkylaryl and C₇–C₂₀ arylalkylradicals, optionally containing one or more atoms belonging to Groups13–17 of the Periodic Table of the Elements; or two R^(a1) substituentsattached to the same atom E¹ or E² form a saturated, unsaturated oraromatic C₄–C₈ ring, having from 4 to 20 carbon atoms; m′ and n′ areindependently 0, 1 or ₂, depending on the valence of E¹ and E², so tosatisfy the valence number of E¹ and E²; q′ is the charge of thebidentate or tridentate ligand so that the oxidation state of M^(a)X^(a)_(p)X^(a)′_(s) or M^(a)A^(a) is satisfied, and the compound (II) or(III) is overall neutral; X^(a), the same or different from each other,are monoanionic sigma ligands selected from the group consisting ofhydrogen, halogen, —R, —OR, —OSO₂CF₃, —OCOR, —SR, —NR₂ and —PR₂ groups,wherein the R substituents are linear or branched, saturated orunsaturated, C₁–C₂₀ alkyl, C₃–C₂₀ cycloalkyl, C₆–C₂₀ aryl, C₇–C₂₀alkylaryl or C₇–C₂₀ arylalkyl radicals, optionally containing one ormore atoms belonging to Groups 13–17 of the Periodic Table of theElements (new IUPAC notation), or two X^(a) groups form a metallocyclering containing from 3 to 20 carbon atoms; X^(a)′ is a coordinatingligand selected from mono-olefins and neutral Lewis bases wherein thecoordinating atom is N, P, O or S; p′ is an integer ranging from 0 to 3,so that the final compound (II) or (III) is overall neutral; s′ rangesfrom 0 to 3; and A^(a) is a π-allyl or a π-benzyl group; and optionallyan Al-alkyl compound or an alumoxane or a compound capable of forming analkyl metallocene cation; and (C) polymerizing one or more of saidolefins CH₂═CHR¹, in one or more reactors, in the presence of theproduct obtained in step (B), wherein the process produces at leastabout 500 grams of a porous olef in polymer per gram of the solidcatalyst component.
 11. A process for polymerizing a heterophasiccopolymer of propylene comprising the following steps: (A) polymerizing,in at least one reactor, propylene or its mixtures with one or moreolefins CH₂═CHR⁴, R⁴ being hydrogen, a C₂–C₂₀-alkyl or a C₆–C₁₂-arylgroup, by a process comprising putting into contact in a polymerizationreactor having a reactor temperature initially at a temperature T¹, oneor more olefins of formula CH₂═CHR¹, R¹ being hydrogen, a C₁–C₂₀-alkylor a C₆–C₁₂-aryl group with a catalyst obtained by reacting a solidcatalyst component in the form of spheroidal particles comprising acompound of Ti or V not containing metal- π bonds and a Mg halide,optionally containing one or more electron donor compounds, with analuminum-alkyl (Al-alkyl) compound, then raising the reactor temperatureup to a polymerization temperature, wherein (I) if the temperature T¹ islower than 40° C., the reactor temperature is raised up to thepolymerization temperature in such a way that, for a time of at leastone minute after the introduction of the catalyst system into thereactor, the reactor temperature is raised up to T² under the followingcondition: $\frac{T^{2} - T^{1}}{m} > 10$  wherein m is the time,expressed in minutes, employed for reaching the temperature T²; or (II)if the temperature T¹ is 40° C. or higher, the reactor is maintained fora time of at least one minute at a temperature ranging from 45° C. to65° C.; thereby producing at least about 500 grams of a polymer per gramof solid catalyst component having a content of units derived from theethylene or the olef in of less than 20% by weight and a content ofunits derived from the propylene of greater than 80% by weight; (B)optionally deactivating the catalyst used under (A) and contacting theproduct as obtained under step (A) with a compound selected from thegroup consisting of: (a) compounds of Ti or V not containing a metal-πbond; (b) compounds of transition metal M containing at least a M-π bondhaving a general formula (I):QL_(l)ZMX¹ _(p)   (I) wherein Q is selected from substituted orunsubstituted cyclopentadienyl radicals, which can carry one or morecondensed cycles, which can contain one or more heteroatoms belonging toGroups 13–17 of the Periodic Table of the Elements; Z has the samemeaning of Q or it can also be ═NR⁶, —O—, —S— and ═PR⁶, R⁶ beingselected from hydrogen, a C₁–C₂₀-alkyl, C₃–C₂₀-cycloalkyl,C₂–C₂₀-alkenyl, C₆–C₂₀-aryl, C₇–C₂₀-alkylaryl or C₇–C₂₀-arylalkylradical which can contain one or more heteroatoms belonging to Groups13–17 of the Periodic Table of the Elements; L is a divalent bridgeconnecting the moieties Q and Z; M is an atom of transition metalselected from the Groups 3 to 10 or the lanthanide or actinide groups ofthe Periodic Table of the Elements (new IUPAC version); X¹, same ordifferent, is a ligand selected from hydrogen, a halogen, R⁹, OR⁹,OSO₂CF₃, OCOR⁹, NR⁹ ₂ or PR⁹ ₂ group, wherein R⁹ is selected fromhydrogen, a C₁–C₂₀-alkyl, C₃–C₂₀-cycloalkyl, C₂–C₂₀-alkenyl,C₆–C₂₀-aryl, C₇–C₂₀-alkylaryl or C₇–C₂₀-arylalkyl radical, optionallycontaining one or more heteroatoms belonging to Groups 13–17 of thePeriodic Table of the Elements; p is an integer of from 0 to 3; l is 0or 1; and (c) late transition metal complex of formula (II) or (III):L^(a)M^(a)X^(a) _(p′)X^(a)′_(s′)  (II)L^(a)M^(a)A^(a)   (III) wherein M^(a) is a metal belonging to Group 8,9, 10 or 11 of the Periodic Table of the Elements (new IUPAC notation);L^(a) is a bidentate or tridentate ligand of formula (VI):

wherein: B is a C₁–C₅₀ bridging group linking E¹ and E², optionallycontaining one or more atoms belonging to Groups 13–17 of the PeriodicTable; E¹ and E², the same or different from each other, are elementsbelonging to Group 15 or 16 of the Periodic Table and are bonded to saidmetal M^(a); the substituents R^(a1), the same or different from eachother, are selected from the group consisting of hydrogen, linear orbranched, saturated or unsaturated C₁–C₂₀ alkyl, C₁–C₂₀ alkyliden,C₃–C₂₀ cycloalkyl, C₆–C₂₀ aryl, C₇–C₂₀ alkylaryl and C₇–C₂₀ arylalkylradicals, optionally containing one or more atoms belonging to Groups13–17 of the Periodic Table of the Elements; or two R^(a1) substituentsattached to the same atom E¹ or E² form a saturated, unsaturated oraromatic C₄–C₈ ring, having from 4 to 20 carbon atoms; m′ and n′ areindependently 0, 1 or 2, depending on the valence of E¹ and E², so tosatisfy the valence number of E¹ and E²; q′ is the charge of thebidentate or tridentate ligand so that the oxidation state of M^(a)X^(a)_(p)X^(a)′_(s) or M^(a)A^(a) is satisfied, and the compound (II) or(III) is overall neutral; X^(a), the same or different from each other,are monoanionic sigma ligands selected from the group consisting ofhydrogen, halogen, —R, —OR, —OSO₂CF₃, —OCOR, —SR, —NR₂ and —PR₂ groups,wherein the R substituents are linear or branched, saturated orunsaturated, C₁–C₂₀ alkyl, C₃–C₂₀ cycloalkyl, C₆–C₂₀ aryl, C₇–C₂₀alkylaryl or C₇–C₂₀ arylalkyl radicals, optionally containing one ormore atoms belonging to Groups 13–17 of the Periodic Table of theElements (new IUPAC notation), or two X^(a) groups form a metallocyclering containing from 3 to 20 carbon atoms; X^(a)′ is a coordinatingligand selected from mono-olefins and neutral Lewis bases wherein thecoordinating atom is N, P, O or S; p′ is an integer ranging from 0 to 3,so that the final compound (II) or (III) is overall neutral; s′ rangesfrom 0 to 3; and A^(a) is a π-allyl or a π-benzyl group; and optionallyan Al-alkyl compound or an alumoxane or a compound capable of forming analkyl metallocene cation; and (C) polymerizing, in at least one reactorat least two olefins selected from those belonging to formula CH₂═CHR¹,R¹ being hydrogen, a C₁–C₂₀-alkyl or a C₆–C₁₂-aryl group and optionallya polyene, in the presence of a product obtained under step (B).
 12. Theprocess according to claim 11 wherein in step (C) ethylene iscopolymerized with propylene and optionally with polyene.